Generally, catalysts used for olefin polymerization can be classified into three categories: traditional Ziegler-Natta catalyst, metallocene catalyst, and non-metallocene catalyst. For traditional propene polymerization Ziegler-Nattacatalyst, titanium catalysts used for propene polymerization mainly use magnesium, titanium, halogen, and electron donor as basic components, wherein electron donor compounds are indispensible elements of catalyst components. With the development of electron donor compounds in catalysts, olefin polymerization catalysts are also constantly undated, and the development thereof experiences the 1st generation of TiCl3AlCl3/AlEt2Cl system, the 2nd generation of TiCl3/AlEt2Cl system, the 3rd generation of TiCl4.ED.MgCl2/AlR3.ED system using magnesium chloride as carriers, monoester or aromatic diester as internal electron donor, and silane as external electron donor, and the newly developed catalyst system using diether compounds and diester compounds as internal electron donors. The activity of catalysts for catalytic polymerization reaction and the isotacticity of the obtained polymers are greatly improved. Till now, many internal electron donor components have been disclosed, these components including, for example, monocarboxylic esters or multiple carboxylic esters, acid anhydrides, ketone, monoethers or multiple ethers, alcohols, amines, and derivatives thereof, and so on, wherein commonly used ones are aromatic dicarboxylic esters such as di-n-butyl phthalate or di-n-butyl diisobutyl ester, and so on. Reference can be made to U.S. Pat. No. 4,784,983, U.S. Pat. No. 4,971,937 and European patent EP0728769 disclose components of catalysts used for olefin polymerization, wherein 1,3-diether compounds having two ether groups are used as electron donors, such compounds including, for example, 2-isopropyl-2-isopentyl-1,3-dimethoxy propane, 2,2-diisobutyl-1,3-dimethoxy propane, and 9,9-di(methoxymethyl) fluorene, etc. Later, aliphatic dicarboxylic ester compounds, such as succinate, malonic ester, glutarate, and so on, are disclosed (see WO98/56830, WO98/56834, WO01/57099, WO01/63231, and WO00/55215). However, catalysts prepared with existing internal electron donor compounds generally have defects such as rapid decrease of activity. Besides, taking diether catalysts as an example, diether catalysts have a high activity, and can obtain a polymer with high isotacticity without external electron donors, and have a good hydrogen response, but the molecular weight distribution thereof is very narrow, and the activity thereof decreases fast while diester catalysts can obtain a polymer with relatively wide molecular weight distribution and rigid-tough balance, the hydrogen response thereof is not that good.
The present invention aims to provide a new catalyst component and catalyst, wherein the catalyst has a high activity and high long-term stability, and can widen the molecular weight distribution of the obtained polymer, and can enable the obtained polymer to have a high melt index and isotacticity. The obtained polymer has a broad application prospect.